Fulvene Synthesis by Rhodium(I)-Catalyzed [2+2+1] Cycloaddition: Synthesis and Catalytic Activity of Tunable Cyclopentadienyl Rhodium(III) Complexes with Pendant Amides.

It has been established that a RhI+ /segphos complex catalyzes the [2+2+1] cycloaddition of 1,6-diynes with cyclopropylideneacetamides to give substituted fulvenes in good yields. The reductive complexation of the product fulvenes with RhCl3 in EtOH furnished the corresponding dinuclear cyclopentadienyl RhIII complexes bearing a pendant amide moiety. These RhIII complexes were highly active catalysts for oxidative annulation and cyclization through C(sp2 )-H and C(sp3 )-H functionalization.